Counterbalance device



Nov. 12, 1940. J. R. MAHAN ETAL COUNTERBALANCE DEVICE Filed Dec. 29,1939 4 Sheets-Sheet l 1%ENTOR9 4C? ATTORNEY Nov. 12, 1940. J. R. MAHANETAL COUNTERBALANCE DEVICE Filed Dec. 29, 1939 4 Sheets-Sheet 2 BY M PINVENTOR-V mm 73. 7M Q ATTORNEY.

Nov. 12, 1940.

J. R. MAHAN ET AL 222L428 COUNTERBALANCE DEVICE Filed Dec. 29, 1939 4Sheets-Sheet 3 4442 TTORNEY Nov. 12, 1940.

J. R. MAHAN ET AL COUNTERBALANCE DEVICE Filed Dec. 29, 1939 4Sheets-Sheet 4 I 4.039 5'2 40 go 53 2 *K 4 INVENTORS. z 91 i w W m. M.1,7 ATTO EY.

Patented Nov. 12, 1940 PATENT OFFICE COUNTERBALANCE DEVICE Joseph R.Mahan and John B. Picard,Toledo,

Ohio, assignors to The National Supply Company, Pittsburgh, Pa., acorporation of Pennsylvania Application December 29, 1939, Serial No.311,544

18 Claims.

This invention relates generally to counterbalance devices for crankshafts of oil well drilling and pumping apparatus and more particularlyto improvements in the construction and the manner of attachingcounterbalance weights to their supports.

The principal object of this invention is the provision of a unitarycounterweight structure and improved means for securing the same to acrank shaft or crank member for use with oil well drilling and pumpingapparatus.

Another object is the provision of an improved arcuate disk-type crankmember arranged to pendulously and slidably support counterweightsadjustably secured thereto.

Another object is the provision of improved double wedge clamping meansfor securing the counterweight to a support.

Another object is the provision of wedge means for securing acounterweight to its support.

Another object is the provision of an arcuate counterweight supportarranged to be secured to a shaft and a counterweight slidably mountedon the support for adjustment to any selected position and lockedthereto by oppositely disposed wedges engaging therebetween.

Other objects and advantages appear from the following description andclaims.

A practical embodiment illustrating the principles of this invention isshown in the accompanying drawings wherein:

Fig. 1 is a perspective view of a pumping unit with parts broken awayshowing a crank shaft having two crank arms with counterweights attachedthereto.

Fig. 2 is a side elevation of the crank arm having counterbalanceweights attached thereto, one of the weights being shown in sectionillustrating the application of the wedge clamping members.

Fig. 3 is a sectional view of a counterweight member.

Fig. 4 is an end elevation of the weightmember applied to the crank armdisk.

Fig. 5 is a perspective view of one of the wedges illustrated in Fig. 2.

Fig. 6 is a sectional view of the counterweight clamping assembly.

7 is a side elevation of a radial crank arm having two counterbalanceweights attached thereto, a portion of each weight being shown insection to illustrate the clamped and unclamped position of the wedgeblocks.

Fig. 8 is a sectional View taken on the line 88 of Fig. '7.

Referring to Fig. 1 of the drawings, Ill represents the base of thepumping unit arranged to support the pumping jack and the operatingmechanism therefor. The base I 0 comprises a pair of steel beams lldisposed in parallel relation and joined together at their ends by thetransverse members l2 welded thereto.

i3 represents a pair of braces welded at their lower ends to the beams Hand inclining upwardly for supporting the Samson post of the jackstructure just below the saddle which is not shown. I i

The crank shaft I4 is rotatably supported in the spacedbearing supports15 each of which is mounted on the spaced beams l l These bearingsupports are cast integral with the reduction gear housing I 6. Thereduction gear drive in the housing operates the crank shaft I4 and thepower is supplied thereto from a motor arranged to be supported on thebed plates I! at the rear of the machine. The bed plate is arranged toreceive either an electric motor or an internal combustion machine,depending upon the class of service required and the location of thepumping unit.

When a double pitman and crank structure is employed the ends of thecrank shaft I4 extend through the bearing in the supports l5 and arearranged to receive the crank members [8. Each crank is provided with aradially extending crank arm l9 having a series of transverse openingsin axial alinement for receiving the wrist pins to which the free endsof the double pitman 2| are journaled.

Each crank arm I9 is provided with a split head 22 which connects withthe transverse opening 23 arranged to receive the end of the crank shaft14. The extended portions of the split head of the crank arm may bedrawn together by the clamping bolts 24, thereby locking the arm to theshaft 14. A key 25 is also provided to prevent relative movement betweenthe crank and the shaft.

The crank member [8 comprises the crank arm I!) and the circular disk 26formed integrally therewith. The disk is preferably disposedeccentrically with respect to the crank shaft opening 23 in the crankarm but it may be concentric and it is not completely circular in thatthe section adjacent the crank head is omitted as shown on the drawings.The perimetral edge of the disk 26 is T-shaped with the flanges 21extending on each side thereof and the ends of which terminate on eachside of the crank arm head 22. Transverse openings are formed throughthe disk 26 below the T-shaped flanges and. adjacent the ends thereoffor receiving the stop plates 28 inserted half way through theseopenings. These plates are held in place by the bolts 23 which passthrough holes in the edges of the disk and screw into tapped holescentrally disposed in the plates. If desired a series of these stopplate openings may be made through the web of the T-shaped perimeter ofthe disk to check the movement of a counterweight beyond the position ofthe plates.

It is preferable to provide each crank member with two duplicatecounterweights 30 and 3|. Each counterweight is a single solid member inthe form of a segment of a sector and has an inverted T-shaped slotforming the grooves 32 in I the arcuate concave edge, which slot iscomplementary to the T-shaped perimeter of the disk 25. Thus when a stopplate 28 is removed the grooves 32 may be moved over the flanges of theT-shaped perimeter of the disk, thereby pendulously supporting theweight from the periphery of the disk and the weight is freely slidablerelative to the disk between the stop plates 28. Thesecounterweights arepreferably unitary but may be partible in a plane normal to the axis ofthe shaft.

The intermediate portion of the undersurface of the inturned flanges 33on the counterweights is receded as indicated at 34 in Fig. 3, therebyproviding the supporting bearing surface 35 adjacent each end of theflanges 33 when the weight is hanging from the disk. If the weight isabove the disk the supporting surfaces 36 on the body of the weight,which are oppositely disposed from the surfaces 35, will support theweight on top of the T-shaped perimeter of the disk.

The slot 31 between the opposed edges of the flanges 33 extends downinto the weight and one 'end is open the full way while the other ispartially closed by the. filler 38. The bottom of thisslotis'disposed atright angles to a plane bisecting the weight and a plurality oflongitudinally extending bearing surfaces 39 raised from the slot bottomadjacent each end thereof form a track of arcuate cross sectional shapefor receiving the weight clamping wedge blocks 40. These wedge blocksare provided with an arcuate under surface 4! which mates with thearcuate bearing surfaces 39 on the slot bottom. A portion of the topsurface of these blocks is inclined as shown at 42 in Fig. and isprovided with fiat longitudinally spaced clamping surfaces 43 arrangedto engage the perimetral surface of the disk 26. inwardly adjacent theflanges 21. The other portion 44 of the top of the wedge blocks remainout of contact with the disk 26 as shown .inFig. 2.

These wedge; blocks fit loosely within the slot 31 of, the weight andare provided with cylindrical lugs 45 extending from each side thereofand arranged to be inserted through grooves 32 into the guiding slotsf46formed in the side faces of weight when it is being adjusted or shiftedon the disk.

The lugs 45 clear the bottom of the grooves '32" and the slots 46,-andthe flat inclined clamping surfaces 43 which engage the perimetralsurface of the disk causethe wedging'blocks to seek their properposition onthe arcuate bearing surfaces 39. Thus the perimetral surfaceof the disk 26, being an unfinished casting, may not be exactly true,causing the wedge blocks to be slightly tilted, but the arcuate matingbearing surfaces provide uniform transmission of the wedging forcesbetween the blocks and the weight.

A hole 41 extends longitudinally through the center of the wedge blocksand is intersected by the well 48 which extends from the top of theblock to a plane below the hole 41. The walls of the well adjacent thesides and large end of the block are straight as indicated at 49 but thewall 50 adjacent the small end of the block is arcuate with the maximumpoint of the curved surface being aligned with the horizontal largediameter of the hole 41 to provide a bearing surface against which theflat face of the clamping nuts 5| and 52 may rock to seek properalignment of the threaded clamp rod 53 to avoid strains on the latter.This clamp rod loosely fits in the holes 41 of the wedge blocks 40.

The clamp rod 53 is provided with a right hand thread 5 3 on one end andthe left hand thread 55 on the other end. These threads are arranged toreceive the nuts 5! and 52 respectively. In assembling, the nuts 5! and52 are inserted in their respective well 48 of the Wedge blocks and areprevented from turning by their engagement with the fiat walls 49 of thewells 48. The small ends of the wedge blocks 40 are placed adjacent oneanother. Both ends of the clamp rod are then screwed into the nuts 5|and 52 by rotating the rod in the direction of theright hand thread.This draws the wedges toward one another in assembled relation and theends of the rod extend through the blocks. The end of the clamp rodwhich is selected for operating the same may have a square or hexagonalend formed thereon. However it is preferable to thread a bearing collaron the rod spaced from the end thereof and to provide the collar with anut as indicated at 5B. The nut and the collar are welded together andto the rod as indicated at 5 The operating nut 56 may be locked by thesleeve 58 having a duodecahedral bore 59 which fits .thereover and isprovided with the lugs 58 extending on each side thereof arranged toengage the outer portion 6! of the slot 31. When the wedges have beentightened the sleeve 58 isplaced over the nut 56, thereby preventing therod 53 from accidentally turning due to vibration or other similarcauses. The sleeve 58 is locked in place by the nut 62. When the clamprod isv to be operated the sleeve 58' and the nut 62 may be removed anda socket wrench applied to the nut 56 to rotate the operating rod 53 tomove the Wedges. 7

When the Wedges 40 have been properly spaced along the operating rod sothat the lugs 45 will drop into the slots 46, the clamping assembly isplaced in the counterweight with the lugs 45 passing through the grooves32 until they are just above the open ends of the slots 46, at whichtime they are permitted to drop therein with the under arcuate surface4| of the wedge blocks resting on the bearing surfaces 39. The operatingrod is then rotated in a counterclockwise direction to draw the wedgeblocks away from one another to clear the grooves 32.

The operating or lead rod 53 should be rotated in this direction untilthe lugs 45 engage the outer ends of the slots 46, using them asreaction surfaces to lock the Wedge blocks in their open position. Whenin this position there is nodanger of these blocks shifting accidentallyand interfering with the assembly or'adjustment of the weights on thedisk.

The counterweight clamping assembly, which is illustrated in Fig. 6, maybe said to fioatand is free to operate in the groove of thecounterweight, It is not secured to the weight and therebyobviates thenecessity of finishing, drilling or machining the weight casting. Thisis an important improvement of this invention.

To assemble the weights on the crank arm the stop plates 28 on the disk26 are removed and the counterweights slid over the T-shaped perimeterwith the flanges 2i riding in the slots 32. When the weights clear theends of the disk the stop plates are secured in position.

When the counterweights have been properly positioned on the disk withrespect to the operating or pumping load the operating rods 53 arerotated in a clockwise direction, thus drawing the wedging blocks 49together and in contact with the rim of the disk, thereby securing theweights against movement. The wedges thus pull the bearing surfaces 35against the under surface of the flanges 21. tween the bearing surfacesof the wedge, acting against 'a circular surface on the perimeter of thedisk, together with the fact that these surfaces are that of anunfinished casting, provides a very tight clamping action preventingrelative movement between the counterweights and the disk.

When it is desired to readjust the Weights on the disk the locking nut62 and washer 58 are removed and a wrench is applied to the nut 55 forrotating the rod 53 in a counterclockwise direction. Owing to the factthat both wedge blocks are engaged between the disk and the weight therotation of the rod backs off the wedge block having the leastresistance to movement while the other wedge block remains inengagement. The wedge block which first backs out of engagement uses theother wedge block as a reaction surface and proceeds to move until thelugs d5 engage the outer ends of the slots 46. The pitch of both theleft and right hand thread is effective in moving this block until it isstopped by the end of the grooves 45 which in turn become the reactivesurface for forcing the. second wedge block out of engagement. Thesecond block then proceeds to the end of its limit of travel at whichtime both blocks are held against the outer ends of their correspondingslots M3 by the screw or What has been referred to as looking the wedgesin their open position.

This is an important advantage of this inventicn as the wedge blocks areheld against movement longitudinally of the groove in the weight by thescrew 53 and vertical movement by the lugs 45 engaging the Walls of theslots 46. Thus when the weight is assembled on the arcuate support thewedge blocks of the floating weight clamp assembly may be locked ateither limit of their travel.

The construction of this clamping assembly permits the use of fillets inthe corners of the casting defining the grooves and slots, therebyproviding added strength to the castings. Again the weights beingpreferably formed as integral unitary structures do not rely on throughbolts for retaining them on the disk or in position, and they may bereadily loosened, adjusted and tightened in any desired position betweenthe stop plates 23.

An economic advantage is gained by the use The acute angle be-v of thisimproved counterweight device in that the rim of the arcuate crank armand the counter- Weights are not machined. The use of the wedge blocksfor locking the weights to the arcuate arm permit the use of unmachinedcoacting surfaces between these castings. Again. the counterweightsbeing preferably made in a single casting represent an economical savingover the ordinary I lously supported. The flanges 2'! and 33 beingstraight obviously require oppositely disposed inclined surfaces for thebearing surfaces 39 in the weight to produce the wedging action. Thisstructure is illustrated in Figs. '7 and 8 wherein the crank member itcomprises the radial crank arm 64 having the head G5 at one end thereofwhich is provided with an opening for receiving the crank shaft it.

The edges of the crank arm are straight and are T-shaped. The inner endsof thefianges forming the T-shaped edge portion terminate at the head 85as indicated at 66. Transverse openings formed through the web portionsadjacent the outer end of the crank arm, receive the stop plates 28which are held in place by the bolts 29 in the same manner as thatdescribed above.

The counterweights 6? and t3 are provided with complementaryT-shapedslots formed by the grooves 32 and the flanges 33 for mounting theseweights on the crank arm. The slots 31 between the opposed faces of theflanges 33 extend into the weight and are open at both ends. Theinclined surfaces 10 at the bottom of the slot 37 of each counterweightare provided with longitudinally extending bearing surfaces ll raisedfrom the slot bottom. These surfaces receive the complementary inclinedsurface of the wedge blocks Mi. These mating surfaces are preferablyarcuateas shown in Fig. 8. The wedge blocks and the clamp rods areassembled and operated in the same manner as that described above.

While for the sake of clearness of illustration, we have shown the useof our improved counterbalance structure in connection with a doublepitman for operating a walking beam, it is obvious that ourcounterbalance structure is equally applicable where a single pitman isused. Again where a load or loads are connected through pull rods to adouble crank or to a back crank the counterbalance mechanism may be usedon either or both cranks.

We claim:

1. In a counterweight device, the combination of a support arranged tobe mounted on a shaft, a counterweight, means interengaging the weight.

and the support for slidably carrying the weight on the support, andwedge means independent of said first mentioned means arranged to engagebetween the weight and the support for securing the weight at anydesired position relative to the support.

2. In a counterweightdevice, the combination of a'support arrangedto bemounted on a shaft, a counterweight, means interengaging the weight andthe support for slidably carrying the weight on the support, a wedgeindependent of said first mentioned means arranged to engage between theweight and the support for securing the Weight at any desired positionrelative to the support, and means for moving the wedge into and out ofengagement.

3. In a counterweight device, the combination of a support arranged tobe mounted on a shaft, a counterweight, means interengaging the weightand the support for slidably carrying the weight on the support, a slotlongitudinally of the edge of the weight adjacent the support, a wedgeblock in said slot, and means for moving said Wedge block longitudinallyof the slot and into engagement with the support for securing the weightto the support in any selected position and for withdrawing the wedgeblock from engagement to permit adjustment of the weight.

4. In a counterweight device, the combination of a support arranged tobe mounted on a shaft,

a counterweight, means interengaging the weight and the support forslidably carrying the weight on the support, a slot longitudinally ofthe edge of the weight adjacent the support, a pair of wedge blocks insaid slot, and means for simul taneously moving said wedge blocks intoengagement with the support for securing the weight to the support inany selected position and for simultaneously withdrawing the wedgeblocks from engagement to permit adjustment of the weight.

5. In a counterweight device, the combination of a support arranged tobe mounted on a shaft, a counterweight, means interengaging the weightand the support for slidably carrying the weight on the support, a slotlongitudinally of the edge of the weight adjacent the support, a wedgeblock in said slot, means for moving said wedge block longitudinally ofthe slot and into engagement with the support for securing the weight tothe support in any selected position and for withdrawing the wedge blockfrom engagement to permit adjustment of the weight, and means forlocking said wedge block moving means to prevent movement of the Wedgeblock in any position.

6. In a counterweight device, the combination of a support arranged tobe mounted on a shaft, a counterweight, means interengaging the weightand the support for slidably carrying the weight on the support, a slotlongitudinally of the edge of the weight adjacent the support, a pair ofwedge blocks in said slot, means for simultaneously moving said wedgeblocks into engagement with the support for securing the weight to thesupport in any selected position and for simultaneously withdrawing thewedge blocks from engagement to permit adjustment of the weight, andmeans for locking said wedge block moving means to preventmovement ofthe wedge blocks in any position.

7. A counterweight support for use on shafts in well pumping apparatuscomprising a unitary member provided with a transverse hole for mountingit on a shaft, a portion of the edge of said member being formed in aT-shaped cross section, one end of the T-o'haped cross section beingopen to receive a weight having a groove complementary to the T-shapededge, a transverse opening through the member adjacent the T-shapedcross section, a plate arranged to be placed in said opening to retain aweight on the T-shaped edge of the support, and means for removablysecuring the plate in place.

8. A counterweight support for use on shafts in well pumping apparatuscomprising a unitary arm member provided with a transverse hole formounting it on a shaft, the opposite edges of the arm being formed inT-shaped cross section, one end of the T-shaped edges being open toreceive weights having grooves complementary to the T-shaped edge,transverse openings through the arm adjacent the T-shaped crosssections, plates arranged to be placed in said openings to retain theweights on the T-shaped edges of the arm, and means for removablysecuring the plates in place.

9. A counterweight support for use on shafts in well pumping apparatuscomprising a unitary sector provided with a transverse hole for mountingit on a shaft, the arcuate edge of the sector being formed in a T-shapedcross section, the ends of said arcuate edge of the sector being open toreceive weights having a groove complementary to the T-shaped edge,transverse openings through the sector adjacent the ends of the arcuateedge, plates arranged to be placed in said openings to retain a weighton the T-shaped edge of the sector, and means for removably securing theplates in place.

10. A counterweight for use on a support attached to the shaft of wellpumping apparatus comprising a unitary member having a slot along oneedge thereof, parallel grooves in the sides of the slot facing oneanother and forming a T- shaped opening for receiving a complementaryedge portion of a support, a bearing surface in the slot, a wedge blockmovable along the hearing surface and having a support-engaging surface,and means for operating the wedge block to move said surface into andout of the engaging position.

. 11. A counterweight for use on a support attached to the shaft of wellpumping apparatus comprising a unitary member having a slot along oneedge thereof, parallel grooves in the sides of the slot facing oneanother and forming a T- shaped opening for receiving a complementaryedge portion of a support, a bearing surface in the slot, a wedge blockmovable along the bearing surface. and having a support-engagingsurface, means for operating the Wedge block to move said surface intoand out of the engaging position, and means for locking the wedgeblock-operating means.

12. In a counterweight device the combination of a support memberarranged to be mounted on a shaft, a counterweight member, one of saidmembers having an extended head of T- shaped cross section, the othermember having an extended slot of T-shaped cross section complementaryto said head, the head and the slot being arranged to interengage forslidably supporting the weight on the support, and wedge means carriedby one of said members'and arranged to engage the other member forsecuring the weight in any desired position relative to the support.

13. In a counterweight device the combination of a support memberarranged to be mounted on a shaft, a counterweight member, one of saidmembers having an extended head of T-shaped cross section, the othermember having an extended slot of T-shaped cross section complementaryto said head, the head and the slot being arranged to interengage forslidably supporting the weight on the support, a pair of wedge blockscarried by one of said members and arranged to engage the other memberfor securing the weight in any desired position relative to the support,means for moving the wedge blocks simultaneously into engagement, andmeans for locking said wedge block moving means.

14. In a counterweight device, the combination of an arcuate supportarranged to be mounted on a shaft and having a T-shaped perimeter, aweight having inturned flanges arranged to fit over the T-shapedperimeter to s-lidably support the weight, and a wedge movable intoengagement between the weight and the support for scuring the weight atany desired position relative to the support.

15. In a counterweight device, the combination of a support arranged tobe mounted on the shaft, a counterweight, means interengaging the weightand the support for slidably carrying the weight on the support, a slotlongitudinally of the edge of the weight adjacent the support and havingan abutting surface adjacent each end thereof, a pair of blocks slidablysupported in said slot between the abutments, each block having surfaceswhich mate in wedging engagement between the weight and the support forlocking the weight in any desired position, and means engaging saidblocks and normally operable to simultaneously move the blocks eithertoward or away from each other, said means locking the blocks whendiverged against the abutments and wedging the blocks in tightengagement between the support and the weight when converged, the blockhaving the least resistance to movement from wedging engagementemploying the other block as the point of reaction for moving it to theadjacent abutment whereupon it engages said abutment and transfers thepoint of reaction 17. In a counterweight device, the combination of asupport arranged to be mounted on a shaft, a counterweight, meansinterengaging the weight and the support for slidably carrying theweight on the support, wedge blocks independent of said first mentionedmeans arranged to engage between the weight and the support for securingthe weight at any desired position relative to the.

support, and a screw for adjusting said wedge blocks, said screw beingwholly supported by said Wedge blocks.

18. In a counterweight device the combination of a support memberarranged to be mounted on a shaft, a counterweight member, one of saidmembers having an extended head of T-shaped cross section, the othermember having an extended slot of T-shaped cross section complementaryto said head, the head and the slot being arranged to interengage forslidably supporting the weight on the support, and means movablelongitudinally of said head and slot to engage and fix the counterweightmember against movement relative to the support.

JOSEPH R. MAHAN. JOHN B. PICARD.

